having pulse difference in two area of laser CO2 machine

Dear all,
thank you for sharing your thoughts and lovely teamwork spirit.
i have laser machine Co2, all the setup is perfect including laser tube,chiller,compressor,table alignments, mirror alignment,etc.
As you know that, when we adjust the lens and mirrors, you have to test the last lens and base on the final pulse test, you will be able to figure out the height of the laser head depends on the pulse dot perfection.
the issue i have, the pulse dot on the right side is perfect but when i move the head to the left side is thicker than the one in the right which of course will reflect in the material cutting in which the laser beam will be thicker so the cutting quality will be effected.

i have tried every thing even checked the floor alignments, but nothing except the inner electronic.

did anyone has the same issue before and hoow it can be solved?

regards,